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General Information on AC Induction Motors
1.1 Definitions
Mode of operation
of 1PH
ALA
Power characteri-
stics
ALA/1-4
Constant torque M
is available from standstill up to the rated operating
rated
point.
The constant power range starts from the rated operating point
(refer to the power/speed diagrams).
At higher speeds, i.e. in the constant–power range, the maximum available tor-
que M
at a specific speed n can be approximated according to the following
max
formula:
[W]
P
max
[Nm] 9.6<
M
max
n [RPM]
AC motors have a high overload capability in the constant–power range. For
several AC motors, the overload capability in the higest speed range is reduced.
The exact data can be taken from the motor characteristics in the appropriate
motor Chapters.
The motor field remains constant in the basic speed range up to the rated motor
operating point. This is then followed by an additional constant–power range.
P, M
P
max
M
rated
P
rated
n
rated
Fig. 1-1
Basic characteristics of power P and torque M as a function of the speed n
(duty types according to VDE 0530 Part 1)
The constant power range, for main spindle drives, with typical machining and a
constant cutting power, can be extremely efficiently used and reduces the requi-
red drive converter rating.
The following limits and characteristics are, from the basic principle, valid for all
main spindle motors –PWM drive converter combinations.
Siemens AG 2000 All rights reserved
S6
S1
SIMODRIVE Planning Guide Motors (PJM) – 11.00 Edition
09.00
n
n
max
6SN1197–0AA20
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